Thursday, November 01, 2007

Beware the plausible hypothesis

So I read Richard Lynn's book. He makes a rather convincing argument for the position that there are significant genetic differences in intelligence among different races. And yet, his argument is almost certainly wrong, and makes a good case study in how difficult it can be to properly interpret data. I'll start by restating Lynn's argument. In fact, I'll go Lynn one better and make an argument that is even stronger than the one he makes. Then I'll show you why it's (almost certainly) wrong.

Let us begin by observing that it is entirely uncontroversial that intelligence has a significant genetic component. Humans are more intelligent than any animal and that is clearly due to the fact that we're humans. Furthermore there are well understood genetic deficiencies in humans (like Down syndrome) that result in marked mental retardation. Furthermore, Down syndrome is also associated with distinctive and easily recognizable physical characteristics, so we have at least one example of a genetic mutation that causes changes is both intelligence and physical appearance. So the hypothesis that there are differences in intelligence among races and that those differences are genetic cannot be ruled out a priori (the way we can, say, claims of perpetual motion) since we have an uncontroversial existence proof that such phenomena do indeed occur.

Furthermore, it is uncontroversial that humans have migrated over periods of time long enough to induce genetic differences among populations. It is clear that differences in skin color is an evolutionary adaptation that has occurred in response to environmental pressures. Lactose tolerance is another very recent example, having evolved as recently as 3000 years ago so even creationists can sign on to that one :-)

Lynn begins his argument by observing that, "There is a widespread consensus that intelligence is a unitary construct that determines the efficiency of problem solving, learning, and remembering." He goes on to give a brief history of the definition of intelligence (which is too long for me to quote here), IQ, and the Flynn effect. He then devotes an entire chapter to discussing the concept of race, addressing the modern notion that the concept of race is a "myth" and showing that even those who advance that view acknowledge that races, as is intuitively obvious to everyone by the most doggedly politically correct, do indeed exist.

The rest of the book is a seemingly unassailable mountain of data showing an indisputably clear and consistent correlation between race and intelligence (as measured by IQ scores). He then shows that intelligence is almost entirely (75-80% depending on the study) a genetically inherited trait by citing studies of identical twins reared apart. Finally, he proposes a plausible mechanism (the evolutionary pressure of having to survive winter) for producing the observed differences in intelligence.

Have I convinced you? There is at least one glaring flaw in the argument above which I introduced on purpose in order to make a point. You might want to see if you can spot it before going on.

BTW, if you are convinced you shouldn't feel bad about it. It's a very convincing argument, and it might even be correct. (It might even be correct despite the flaw.) I am not aware of any data that would falsify it. But it is nonetheless almost certainly wrong. Here's why.

Let's start with my motivating example, Down syndrome, which is indeed a genetic disorder that produces both profound mental retardation and easily identifiable physical traits. However, while Down syndrome is genetic, it is not inheritable. Down syndrome results when an individual gets an extra copy of chromosome 21, which happens during meiosis or gestation. In fact, if you trust Wikipedia (which you really shouldn't, but what the hell) the non-inheritability of Down syndrome leads some researchers to use parents of children with Down syndrome as controls for studies of autism which is apparently at least partially heritable.

So the fact of the matter is that there are no precedent phenomena for the claim that there are genetic differences that result in correlated mental and physical differences within a species. (Obviously there are such differences across species.) This is not to say that it doesn't happen, just that if it happens it is not common. The a priori plausibility of the claim is much lower than the above argument would lead one to believe.

I introduced the Down syndrome argument as a deliberate red herring to make the point that even glaring flaws in an argument are not always immediately obvious even when you are primed for them. Lynn's argument has no flaws quite so glaring as that one (he's not a crackpot). Instead, Lynn's argument contains lots and lots of little flaws that together add up to an argument that is almost certainly wrong. Let's start to explore those.

The foundational flaw in Lynn's argument is the claim that intelligence "is a unitary construct", that it can be reduced to a single number (IQ), that that number can be reliably measured, and that the resulting measure has a causal relationship to something of consequence like the ability to survive winters or build industrial economies. If you read closely, he doesn't actually provide any evidence that this is the case (because there isn't any), he only says that "there is a widespread consensus." Now, this is actually true. There is indeed a widespread consensus. But just because there is a widespread consensus does not mean that it is actually true. As recently as a few decades ago there was a widespread consensus that homosexuality was a mental disease. At various times in history one could find a widespread consensus that bleeding, thalidomide, and Vioxx were effective treatments for various ailments.

In fact there is no evidence that IQ tests measure anything beyond a person's ability to do well on an IQ test. And there is a good reason for this. There are some cognitive abilities (like short term memory capacity, visual acuity, and spatial reasoning) that can be measured objectively, just as we can objectively measure certain physical abilities (like raw strength and speed). But the applicability of these abilities to real-world situations is limited. The holy grail of intelligence testing is a person's overall ability to solve novel problems, and therein lies the rub because a novel problem can only be novel once. I do really well on IQ tests but that's because I'm a geek and I spent a lot of time solving puzzles when I was a kid. I'm really good at solving puzzles, and particularly good at solving the kinds of puzzles that people tend to put on IQ tests. But it is far from clear whether my puzzle-solving skill is a result of some innate ability that I have, or whether it's simply because I've had a lot of practice. There is no way to know which way the causality runs.

It's like this for any kind of complex skill. Is Tiger Woods a superior golfer because he has the golfing gene (and does he have it because of or despite the fact that he's black), or is it simply because he's been golfing continuously since he was three? To really find out you'd need to do an experiment with a statistically significant number of subjects all going through the same intensive training that Tiger Woods went through, and even then you wouldn't really know because it's possible that one kid has a lot of innate golfing skill but just doesn't like golfing enough to really apply herself. The number of factors that go into making an effective golfer or an effective computer programmer or an effective businessman or an effective politician or even an effective puzzle solver are so diverse and varied that it would be impossible to design a study that could tease all these factors apart and give you a statistically significant result.

It gets worse. If you're testing the hypothesis that genes cause both dark skin and decreased "intelligence" (whatever that means) it is impossible to create a control group because it is impossible to hide the fact that a person with dark skin has dark skin. It is therefore impossible to eliminate the subtle effects of societal prejudices. Even if we take all of Lynn's data at face value, all we've shown is that people with dark skin don't do as well on IQ tests as people with light skin. But this could simply be due to the fact that people with light skin happen to live under circumstances that are conducive to the development of IQ-test-taking skills. And I don't just mean better economic conditions, I mean a pervasive belief shared by light-skinned and dark-skinned people alike that light-skinned people are somehow superior. Such a belief can become a self-fulfilling prophecy, and the problem with self-fulfilling prophecies is that they are actually fulfilled. Such beliefs can become self-reinforcing because they are actually true but not because of anything genetic, rather they are true simply because people believe them, rather like a mass (anti-)placebo effect.

The problem is that there is no way to experimentally resolve this. To do so you would have to have a way to make black people look like white people (or vice versa), and that's just not possible. So at this point we have two equally plausible hypotheses to explain the data. How do we decide between them? And in particular, how do I justify my claim that Lynn is "almost certainly wrong"?

Well, let's look at the data. The first thing you notice is that the actual numbers are not nearly as consistent as Lynn would have you believe. To cite just one example that I found leafing through the tables, his data for Zambia are based on two studies, one of which puts the average IQ of Zambians at 77 and the other at 63, very nearly a full standard deviation of difference. And such discrepancies are not unusual.

But let's leave that aside for a moment and take Lynn's data at face value. Consider the unfortunate inhabitants of Cameroon, with an average IQ of 64. Or Equatorial Guinea with an average of 59. These figures are so low as to fall into the range of mild mental retardation. Compared to the Chinese at the opposite extreme with an average IQ of 105 the difference is more than two standard deviations. That seems like an implausibly high variance to be due to genetic factors. To be sure, differences of this magnitude in physical traits are certainly possible -- skin color comes to mind as an example -- but they are rare, and intelligence is much more complex than melanin production.

There's a lot more that could be said about this (and has been but I don't have time to write a treatise. I'll just point out one more problem with Lynn's methodology, one that is more serious than any I have cited so far.

On page 5 of Lynn's book he writes:

The metric employed for the measurements of intelligence f the races has been to adopt an IQ of 100... for Europeans in Britain, the U.S., Australia and New Zealand as the standard in terms of which the IQ's of other races can be calculated. The mean IQ's of Europeans in these four countries is virtually identical.

Notice anything oddly coincidental about those four countries? In all four, English is the native language. So Lynn's definition of intelligence, his gold standard, is the performance of English-speaking people on IQ tests. Don't you think that this definition might introduce just the teensiest bit of cultural bias into the whole endeavor? Besides the winter-induced-genetic-drift hypothesis and the self-fulfilling-prophecy hypothesis we can introduce a third plausible theory to explain Lynn's results, that "intelligence" is just a measure, at least in part, of the ability to learn to speak English. How well do the data support this theory? Well, the Chinese data seems to refute this, but how to explain e.g. the Lithuanians, who at an average IQ of 90 are significantly below their anglophonic cousins? And Lithuania is not exactly known for being a tropical paradise. If having to deal with winter makes you smart, why aren't the Lithuanians geniuses? Why are the Chinese so much smarter than the Innuit? Why are Italians smarter than the Portugese? In these last two examples the differences are huge: a full standard deviation.

The fact of the matter is that intelligence is a monstrously complex phenomenon governed by both genetics and environmental factors. The hypothesis that genetics are the dominant factor, and that adaptation for survival in winter is the driving force, is not in fact supported by the data. And in fact there is one final argument that I think puts the final nail in Lynn's argument: if intelligence is so crucial to winter survival, why do we not see the same differences in intelligence in animals? Why is it that the most intelligent land animals (great apes and elephants) evolved in Africa and not in Europe?

I am open to the possibility that the neo-eugenicists might still be correct. But until someone comes up with a much better argument than Lynn's (and Lynn's is the best they have) anyone who advances the position that blacks are genetically inferior to whites is a bigot in my book.

12 comments:

I am pleased. If the strongest argument you can come up with is that "IQ doesn't mean anything and there's no evidence for it", then the results are in. Information on correlation between IQ and various objective outcomes is very easy to find. You're resorting to a cop-out.

I can't say that I am satisfied with all of the studies that Lynn includes - in some cases I think the samples are simply too small to be reliable. For example, I wouldn't rely on the measurements being very accurate for Serbia - as well as, for that matter, many other places.

But your accusation of culturally biased tests is unfounded. The book does actually include results of tests developed by an African to measure intelligence in an African environment. The results were consistent with western-developed tests.

I don't think we need to be rocket scientists to understand that people whose counting words never developed beyond one-two-few-many probably aren't the brightest of the lot; especially when IQ tests confirm this. (Granted, in some of these languages, it's possible to express concepts up to "seven" as "two-two-two-one". Then it gets too complicated.)

I think Lynn's work definitely leaves room for possible speculation about the possible reasons for, and refinement of our knowledge of, for lots of things - e.g. why is the IQ of Poland so low, and why is it so high for Ashkenazi Jews living outside of Israel?

It is tempting to speculate, e.g. that in the case of countries such as Poland, perhaps the sample was biased, or perhaps the smartest people (those with anti-communist opinions and beliefs) were shot or exiled after WWII. (This happened across ex-Yugoslavia, masses were executed to ensure conformity.)

It is tempting to speculate that, in the case of Ashkenazi Jews (average 115), perhaps again the sample was biased; or perhaps the European-descent Jews who now live across the world are the progeny of the smarter ones who for centuries had successfully anticipated and avoided dying in various persecutions.

But all these uncertainties do not change the underlying facts that: yes, a difference in IQ does indicate a real difference in mental ability (one-two-few-many); and, well... the IQs of sub-Saharan Africans, and native Americans, and native Australians are significantly lower. I'm sad to say that; it would be more convenient for me if they weren't; I'd like the world better if they weren't. But they are.

Now, as for this:

"So the fact of the matter is that there are no precedent phenomena for the claim that there are genetic differences that result in correlated mental and physical differences within a species. (Obviously there are such differences across species.)"

This is fairly disingenious. How then do the differences between species appear in the first place?

I hope you won't accuse me of "scientific sloppiness" and "mistaking consensus for fact" if I suggest that "there is a widespread consensus" (hopefully not one that will be overturned in the following 10 years, right?) that most species today living have evolved from a common ancestor, which means that obviously the species' respective ancestors started out as similar, and then the differences accumulated gradually over time.

For example, if you were able to look back at the ancestors of modern people and chimpanzees at the time our ancestors were diverging, it would be difficult to say at which exact point the two became two separate species, rather than two somewhat distinct collections of individuals within one. But despite that exact point being difficult to determine, you would nevertheless see differences accumulating over time. Why would IQ not be one of them?

I think it makes a lot more sense to assume that IQ is just another characteristic that can diverge in genetically distinct groups; there is no clear reason why the comparative difficulty of measuring IQ should make it less likely to diverge than other, more easily measurable characteristics, such as skin color or hair type. In fact, I think that this is so self-evident, that the onus is actually on those who wish to believe otherwise to prove that there is evidence that IQ is not a characteristic that can similarly diverge.

Good review. I was just about to read this book myself. Perhaps now I won't bother.

A couple of nits, though. (In backwards order :-) )Your strongest criticism is about the winter thing, but that's obviously the weakest part of the story and just tacked on for thought. It may be an interesting hypothesis for future investigation; I don't think that the basic controversy (of race & intelligence) depends on the winter thing.

IQ 100 for English speakers: this was a useful observation in the past, but all followup studies and efforts suggest no particular link between speaking English and IQ. All non-English IQ tests wind up with the same basic results as the original ones; east asians are generally at the top anyway (not European whites), etc. We may not know what is going on, but cultural and language bias is a poor explanation for the observed results.

On the observed national variations in IQ, you say: the difference is more than two standard deviations. That seems like an implausibly high variance to be due to genetic factors. It's important to distinguish two things. One is whether there exists a significant race-based difference in average IQ. The second is the measured IQ in different nations. Everybody knows that final IQ is a mix of genetics and environment. So the huge ranges seen in national comparisons are not solely due (even by hypothesis) to "genetic factors". The low-scoring countries also have horrible environments for IQ. The question still remains whether the gene pools of the different populations differ significantly (with regards to intelligence).

You write: In fact there is no evidence that IQ tests measure anything beyond a person's ability to do well on an IQ test. I think this is just false. Performance on IQ tests is highly predictive of all sorts of other things. You claim to understand your own performance: I do really well on IQ tests but that's because I'm a geek and I spent a lot of time solving puzzles when I was a kid. and you attribute it to interest and practice. But I'm far less confident than you that you've correctly identified the cause of your high IQ scores. Practice and training does not seem to be a reliable way to significantly raise IQ scores in children.

The truth seems to be that there are a lot of environmental things you can do to harm intelligence/IQ. But once you have a normal, adequate upbringing, it is far harder to raise IQ. For people/nations with very low IQ, environment may appear to be responsible for 70-80% of the variance in individual IQ. But once you get to a "normal" (western, US) level of education, nutrition, etc., that variance quickly drops to near zero, and almost all the remaining variance seems to come from a genetic influence. Your genes give you potential, and your environment allows you to reach that potential (or not). But that potential seems to be a pretty hard wall, and there aren't really reliable training methodologies for breaking through that wall. (To turn ordinary, non-deprived students into geniuses, for example.)

Finally, I thought I got your Down's red herring concept, but I didn't understand this: there are no precedent phenomena for the claim that there are genetic differences that result in correlated mental and physical differences within a species. I don't see why you were obsessing about having correlated mental and physical differences. Surely the whole topic is sufficiently interesting with a genetic basis for purely mental ability (intelligence), without bringing in a need for a corresponding (obvious) physical change at the same time?

The rest of your review I won't comment on because I basically agree with you (and also I haven't yet read the book!).

I am pleased. If the strongest argument you can come up with is that "IQ doesn't mean anything and there's no evidence for it", then the results are in.

Yes, and if wishes were horses beggars would ride.

Information on correlation between IQ and various objective outcomes is very easy to find.

OK, everyone, repeat after me: correlation does not imply causality.

But your accusation of culturally biased tests is unfounded.

I didn't say that the tests were culturally biased (though they clearly are). I said that Lynn's definition of IQ was culturally biased, since it defines the baseline IQ in terms of the performance exclusively of English-speaking people.

The book does actually include results of tests developed by an African to measure intelligence in an African environment. The results were consistent with western-developed tests.

Which test was that? (And, only one? And how are you going to normalize the results of a test written in English with one written in Swahili?)

I don't think we need to be rocket scientists to understand that people whose counting words never developed beyond one-two-few-many probably aren't the brightest of the lot; especially when IQ tests confirm this. (Granted, in some of these languages, it's possible to express concepts up to "seven" as "two-two-two-one". Then it gets too complicated.)

That has never been in dispute. What is in dispute is whether these same people would still perform so poorly if they had grown up speaking a different language, with different educational opportunities, or if their skin were a different color.

It is tempting to speculate, e.g. that in the case of countries such as Poland, perhaps the sample was biased, or perhaps the smartest people (those with anti-communist opinions and beliefs) were shot or exiled after WWII. (This happened across ex-Yugoslavia, masses were executed to ensure conformity.)

I need to write an entirely separate post about why this kind of post-hoc analysis is invalid.

But all these uncertainties do not change the underlying facts that: yes, a difference in IQ does indicate a real difference in mental ability (one-two-few-many); and, well... the IQs of sub-Saharan Africans, and native Americans, and native Australians are significantly lower.

Again, that is not in dispute. What is in dispute is whether those differences are genetic. Why is it so hard for you to keep your eye on the ball?

"there is a widespread consensus" (hopefully not one that will be overturned in the following 10 years, right?) that most species today living have evolved from a common ancestor, which means that obviously the species' respective ancestors started out as similar, and then the differences accumulated gradually over time.

Of course. But what Lynn claims is that two completely different traits, one physical and one mental, are evolving in lockstep. And that he has failed to show.

For example, if you were able to look back at the ancestors of modern people and chimpanzees at the time our ancestors were diverging, it would be difficult to say at which exact point the two became two separate species, rather than two somewhat distinct collections of individuals within one. But despite that exact point being difficult to determine, you would nevertheless see differences accumulating over time. Why would IQ not be one of them?

Again, you are missing the point. That intelligence (and even IQ) is at least partially genetic is not in dispute. That it evolves is not in dispute. What is in dispute is whether or not it evolves in a causal relationship with skin color in humans. It could, but Lynn has failed to show that it does (and so have you).

Your strongest criticism is about the winter thing, but that's obviously the weakest part of the story and just tacked on for thought.

No, it's the core of the theory. Scientific theories have to explain something.

There's a classic story about a scientist who went to a native village and found a strong correlation between intelligence and shoe size, with the puzzle being to figure out why. The answer, of course, is that he measured everyone in the village including children. Absent this explanation, one might be tempted to apply intervention therapies to increase intelligence by getting people to wear bigger shoes.

IQ 100 for English speakers: this was a useful observation in the past

This is not an observation, it's the definition of what it means to have an IQ of 100.

All non-English IQ tests wind up with the same basic results as the original ones

Really? How exactly do you administer a non-English IQ test to someone who only speaks English?

Everybody knows that final IQ is a mix of genetics and environment. So the huge ranges seen in national comparisons are not solely due (even by hypothesis) to "genetic factors". The low-scoring countries also have horrible environments for IQ. The question still remains whether the gene pools of the different populations differ significantly (with regards to intelligence).

Not according to Lynn. He cites identical twin studies to support the claim that IQ is 75-80% genetic. Of course, it is unclear how many subjects there were where one was raised in England the other one in Cameroon.

You write: In fact there is no evidence that IQ tests measure anything beyond a person's ability to do well on an IQ test. I think this is just false. Performance on IQ tests is highly predictive of all sorts of other things.

Of course. The question is whether or not it is a causal relationship. Shoe size is highly predictive of a persona ability to perform well on a wide variety of tasks too.

You claim to understand your own performance: I do really well on IQ tests but that's because I'm a geek and I spent a lot of time solving puzzles when I was a kid. and you attribute it to interest and practice. But I'm far less confident than you that you've correctly identified the cause of your high IQ scores. Practice and training does not seem to be a reliable way to significantly raise IQ scores in children.

It seems to work well for other standardized tests. What makes IQ tests different? (And what evidence do you have to support your claim?)

The truth seems to be that there are a lot of environmental things you can do to harm intelligence/IQ. But once you have a normal, adequate upbringing, it is far harder to raise IQ. For people/nations with very low IQ, environment may appear to be responsible for 70-80% of the variance in individual IQ. But once you get to a "normal" (western, US) level of education, nutrition, etc., that variance quickly drops to near zero, and almost all the remaining variance seems to come from a genetic influence.

Evidence?

Your genes give you potential, and your environment allows you to reach that potential (or not). But that potential seems to be a pretty hard wall, and there aren't really reliable training methodologies for breaking through that wall. (To turn ordinary, non-deprived students into geniuses, for example.)

For the nth time, this is not in dispute. What is in dispute is whether skin color is a strong predictor of this potential (better than, say, shoe size).

Finally, I thought I got your Down's red herring concept, but I didn't understand this: there are no precedent phenomena for the claim that there are genetic differences that result in correlated mental and physical differences within a species. I don't see why you were obsessing about having correlated mental and physical differences.

Because that is the point of disagreement. No one disputes that there is variation in intelligence. No one disputes that this variation is correlated with skin color. What is in dispute is whether the mechanism responsible for this correlation is genetics or something else, like a self-fulfilling prophecy, or a built-in definitional bias towards English speakers.

Surely the whole topic is sufficiently interesting with a genetic basis for purely mental ability (intelligence), without bringing in a need for a corresponding (obvious) physical change at the same time?

Don: "The truth seems to be that there are a lot of environmental things you can do to harm intelligence/IQ. But once you have a normal, adequate upbringing, it is far harder to raise IQ. For people/nations with very low IQ, environment may appear to be responsible for 70-80% of the variance in individual IQ. But once you get to a "normal" (western, US) level of education, nutrition, etc., that variance quickly drops to near zero, and almost all the remaining variance seems to come from a genetic influence. Your genes give you potential, and your environment allows you to reach that potential (or not). But that potential seems to be a pretty hard wall, and there aren't really reliable training methodologies for breaking through that wall. (To turn ordinary, non-deprived students into geniuses, for example.)"

This gives hope for Africa in the sense that malnourishment, disease etc may be harming people's development.

However, I wouldn't be as optimistic to say that environment accounts for 70-80% of their, umm, lag. Lynn includes results of tests on college-going people in South Africa; here, still, black students lag significantly behind white, with the notable exception of Maths and Physics students.

Ron: denis: "Information on correlation between IQ and various objective outcomes is very easy to find." - OK, everyone, repeat after me: correlation does not imply causality.

So you're saying it's possible to have all-around very competent people with IQ 70?

We should not close our minds from the possibility that it can happen?

And the Flying Spaghetti Monster, we shouldn't close our minds to that, either? :)

Ron: I need to write an entirely separate post about why this kind of post-hoc analysis is invalid.

You need not. I wrote that "it is tempting to speculate". It is tempting to speculate. Doesn't mean that it is valid.

It's fun, though.

Ron: What is in dispute is whether those differences are genetic. Why is it so hard for you to keep your eye on the ball?

See my response to Don.

And, perhaps would be easier for me to keep my eyes on your ball if it bounced around somewhat less erratically. ;)

Ron: But what Lynn claims is that two completely different traits, one physical and one mental, are evolving in lockstep.

No one's claiming that they necessarily need to be evolving in lockstep. It's totally conceivable that a hypothetical race of super-intelligent coal-black-skinned people could arise. In fact, it's simple: take a bunch of coal-black-skinned people, and then for generations, select them for higher IQ.

The fact that there's a correlation between skin color and average IQ is I think a matter of coincidence. It just so happens that several groups of humans evolved separately under different environmental pressures, and some were selected for IQ more so than others. It so happens that the largest group of those who weren't selected strongly for IQ happen to be dark-skinned.

So what?

Doesn't change the fact that there appears to be a large pool of humans who were not strongly selected for IQ.

Ron: He cites identical twin studies to support the claim that IQ is 75-80% genetic. Of course, it is unclear how many subjects there were where one was raised in England the other one in Cameroon.

This seems to be your strongest argument so far.

It can be tested.

A developed nation could offer to adopt a large random sample of a poor nation's children at a young age. These would be reared by qualified adopting families in the developed nation. Test their IQs at age 18.

To the extent their average IQ is higher than 65, the reasons for Africa's mental lag are environmental. To the extent that their average IQ is lower than 100, it's genetic.

But hey, I think someone actually did this experiment, kind of. They imported a bunch of sub-Saharan Africans to a more developed country. That was centuries ago. Now, the descendants of these people grow up in environments where there is plenty food, and they have access to schools and medicine. Meanwhile, their genes have mixed significantly with those of the other residents, and their average IQ is 85.

Hmm. Go figure? :)

Ron: What is in dispute is whether the mechanism responsible for this correlation is genetics or something else, like a self-fulfilling prophecy, or a built-in definitional bias towards English speakers.

Hmm, I may not have a proof, but I think I know what the mechanism is for your thinking:

"The introduction of a new cognition that is dissonant with a currently held cognition creates a state of "dissonance," the magnitude of which relates to the relative importance of the involved cognitions."

...

"This leads some peoples who feel dissonance to seek information that will reduce dissonance and avoid information that will increase dissonance. People who are involuntarily exposed to information that increases dissonance are likely to discount that information, either by ignoring it, misinterpreting it, or denying it."

Ron: "Ad-hominem attacks are always the last refuge of the person trying desperately to cling to an untenable position."

If that is so, you are comitting the same error in indulging in a reciprocal ad-hominem attack.

The reason I suggested that is because I get the distinct impression that one of us is married to an ideal - and it's not me.

Rarely are we presented with 100% solid evidence for anything in life. More often than not, we need to assess probabilities and act.

Ideology compels us to keep sticking to our theories even if empirical evidence indicates this is unlikely to be truthful. In this case we stick to our theories longer than we should; some want proof with 90% probability, some want proof with 99% probability, some want proof with 99.999% probability until they admit their theory is false.

A reasonable, unbiased person switches sides much sooner. In fact, the ability to switch sides - and not to stick to cherished theories - as soon as credible opposing evidence arrives is what distinguishes a successful trader, or a successful poker player, from an unsuccessful one. George Soros once said, and I paraphrase, that in the financial world, one cannot be married to ideas. One cannot have pride. Even if you were convinced up to a point that a certain theory is correct, and you were acting upon it - as soon as you learn of convincing opposing evidence, you need to be able to turn on a dime.

I found that insight very convincing. There is no value to be had from pride. I'm not sticking to my guns here because I believe in an ideal. I'm sticking to my side because that's where I see the weight of evidence lies. If I see evidence that makes me think differently, I'll switch sides. I have no pride to swallow.

In your case, however - and you should not perceive this as an ad hominem attack, because it isn't; it is merely my considered opinion - it appears that larger things depend on whether or not you accept this evidence to be true. If the mental lag of most of the people in this world is, in fact, genetic, this would have consequences for your most deeply held beliefs, which seem to have to do with social justice, righteousness, and all people being equal. If the reasons for disparities in IQ are wholly environmental, then the causes are societal, which is something for which you've been fighting for a long time, and you can continue as usual. But if the reasons for disparities are in fact genetic, then a lot of your mental investment is at stake, and at risk of losing grounds on which it's built on.

Ron, I sympathize. It is not my intention for my closed mind to "defeat" your closed mind and then claim "victory". There is no victory in prevailing with one's closed mind. But there is benefit to keeping our minds open.

Ron: But what Lynn claims is that two completely different traits, one physical and one mental, are evolving in lockstep.

I was so bewildered by what this argument before that I didn't know how to respond. Not because of the argument's strength, but because I didn't know what you might possibly mean by it that would make sense to me. How is it a problem, or a theory's deficiency, if it observes distinct and unrelated characteristics propagating from generation to generation in a group that is relatively closed genetically?

Let me illustrate with a few examples. Suppose we observe that the Japanese have (1) different shaped eyes than Caucasians, and (2) darker hair (as there aren't any blondes).

How do you explain the preposterous theory that these two seemingly unrelated characteristics have been "evolving in lockstep"? Someone needs to come forth and explain the reasons for this correlation immediately!

Example 2. Suppose we observe that African Americans have (1) darker skin than Caucasians on average, and (2) an increased risk of cardiovascular disease, traced to specific variations in certain genes that are common in African Americans but less common in Caucasians.

How do you explain the preposterous theory that darker skin and increased risk of cardiovascular disease have been "evolving in lockstep"? Someone needs to come forth and explain the reasons for this correlation immediately!

Later you go on to state this:

"The fact that there's a correlation between skin color and average IQ is I think a matter of coincidence."

That would be one hell of a coincidence. I challenge you to compute the odds against it and then come back here and defend that position.

That statement seems totally nonsensical to me. What are the odds of the Japanese having both (A) genes for a certain eye shape and (B) genes for black hair? Why would that evolve simultaneously?

What are the odds for Africans having both (A) genes for dark skins and (B) genes that increase their risk for cardiovascular disease? Why would that evolve simultaneously?

I mean - you're using probability theory in a totally inappropriate post-hoc mode of operation here. We already know that a correlation exists. This means that the likelihood of the correlation having developed genetically in the first place is immaterial. Once you observe that seagulls have beaks and are white, the probability of seagulls evolving both with (1) beaks and (2) white feathers is irrelevant. The likelihood in the world you live in is 100%; it has already happened. It doesn't matter what the original probability was to begin with.

And - crucially - just because the probability of some group evolving both with characteristic A and characteristic B was low to begin with, that doesn't provide you with any grounds for discounting the possibility that the characteristic B is genetic. When the correlation is already observed to exist, it doesn't matter what the probabilities were to begin with!

On the other hand, what would help you is if you knew the initial probability of a correlation between A and B evolving genetically, and the probability of the correlation evolving for any other reason. Suppose the probability of a correlation occuring genetically is 0.025%, and the probability for the same correlation occuring environmentally is 0.075%.

Then, if you knew that a correlation exists, and you had these probability figures - unfortunately nearly impossible to calculate with reliability in the first place - you would be able to say that there is, say, a 25% probability that the correlation is genetic, and a 75% probability that it is environmental.

In this particular case, I would say that an environmental explanation is significantly less probable than a genetic one, because while it is likely that an environmental correlation will occur in particular cases, it seems much less likely that it will occur so consistently across so many countries, different tests, different teams, different decades. I don't have Lynn's book at hand any more because of my move across the Atlantic, but I believe it had results of IQ tests for people of African origin done not just in the States and in Africa, but also in Japan and possibly some European countries as well. That environmental factors would somehow come together without fail in all these cases seems very unlikely to me, and indeed favors a genetic correlation strongly.

Wow, you are apparently much more confused about how science works than I thought. Complete answers to your questions will have to wait for the sequel to the Science 101 post where I plan to talk about the difference between controlled and epidemiological studies. But you appear to be confused about some very basic things which I will try to address here and now.

How is it a problem, or a theory's deficiency, if it observes distinct and unrelated characteristics propagating from generation to generation in a group that is relatively closed genetically?

Let me illustrate with a few examples. Suppose we observe that the Japanese have (1) different shaped eyes than Caucasians, and (2) darker hair (as there aren't any blondes).

How do you explain the preposterous theory that these two seemingly unrelated characteristics have been "evolving in lockstep"? Someone needs to come forth and explain the reasons for this correlation immediately!

Indeed they do. As far as I know it is a mystery why these two traits should co-evolve, and fame and fortune (well, fame at least) awaits the person who figures it out.

The difference between your example and the matter at hand is that no one believes that eye shape is heavily influenced by environmental factors whereas performance on IQ tests clearly is.

Example 2. Suppose we observe that African Americans have (1) darker skin than Caucasians on average, and (2) an increased risk of cardiovascular disease, traced to specific variations in certain genes that are common in African Americans but less common in Caucasians.

How do you explain the preposterous theory that darker skin and increased risk of cardiovascular disease have been "evolving in lockstep"? Someone needs to come forth and explain the reasons for this correlation immediately!

Yes. That is exactly right. This correlation does indeed cry out for an explanation.

Dennis: The fact that there's a correlation between skin color and average IQ is I think a matter of coincidence."

Ron: That would be one hell of a coincidence. I challenge you to compute the odds against it and then come back here and defend that position.

Dennis: That statement seems totally nonsensical to me. What are the odds of the Japanese having both (A) genes for a certain eye shape and (B) genes for black hair? Why would that evolve simultaneously?

Look, you are the one who said that it was a coincidence, not me. I don't believe it is a coincidence. I believe there is a causal factor involved. I believe we actually agree on this. Where we disagree is that I believe that the jury is out about whether this causal factor is genes or environment whereas you believe the evidence clearly show's it's genes.

What are the odds for Africans having both (A) genes for dark skins and (B) genes that increase their risk for cardiovascular disease? Why would that evolve simultaneously?

I don't know. I'm not a biologist. But I can point to another example where I do know the answer. People with dark skin are more likely to develop sickle-cell anemia because sickle-cell is an adaptation that provides protection against malaria, and malaria exists only in tropical climates. Another example: Lactose-tolerance is more prevalent among light-skinned people because lactose-tolerance is an adaptation that aids survival in cold climates (but not too cold -- lactose tolerance only helps if the cows can still survive).

Once you observe that seagulls have beaks and are white, the probability of seagulls evolving both with (1) beaks and (2) white feathers is irrelevant. The likelihood in the world you live in is 100%; it has already happened. It doesn't matter what the original probability was to begin with.

No, you are wrong about that. It is a perfectly legitimate question to ask why seagulls should have both beaks and white feathers, just as it is legitimate to ask why flamingos should have both beaks and pink feathers. The answers to those two questions are not the same, by the way. I'll leave it as an exercise to fill in the blanks for now, but it actually turns out that the reason flamingos are pink is in fact related to the shape of their beaks, but their feather-coloring is not genetic!

Thanks, by the way, for bringing up this really excellent example!

And - crucially - just because the probability of some group evolving both with characteristic A and characteristic B was low to begin with, that doesn't provide you with any grounds for discounting the possibility that the characteristic B is genetic.

In the absence of evidence that it is genetic and a good argument about why it should be genetic it certainly does provide me with grounds to question the proposition that it is genetic. And I say again, mere correlation is not evidence of causality. The reason Flamingos are pink is not that they have genes for pink feathers.

When the correlation is already observed to exist, it doesn't matter what the probabilities were to begin with!

Of course it matters. Consider the following three theories to explain the correlation between IQ and race:

1. It's genetic2. It's environmental3. It's the result of aliens implanting probes in the brains of white people to make them smarter

I presume you will agree that theory 3 can be discounted without further deliberation despite the fact that you cannot prove it to be false. So what is your basis for discounting it?

But that doesn't mean I'm misunderstanding what is taking place. You have yet to show that. While I think highly of your posts like "Science 101", in that by writing them you are sharing valuable insight and knowledge; and while I do think that you know things I can learn - I also think that you are overestimating my ignorance.

But I'll wait for "Science 102" to see. ;)

I presume you will agree that theory 3 can be discounted without further deliberation despite the fact that you cannot prove it to be false. So what is your basis for discounting it?

I responded to this in my next post. Suppose the prior probabilities are 0.025% for A, 0.074% for B, and 0.001% for C. Then we can discount C because, once we have observed that either A, B, or C must be taking place, the likelihood is 99% that it's either A or B, and only 1% that it is C.

But like I said, that doesn't help you much here because you don't really know - and can't accurately determine - what the prior probabilities are to begin with. Perhaps it is the alien theory.

The real reason why we don't admit the alien theory is because it has no "explainability"; in the sense it's a theory that can explain anything, cannot be used to make predictions, and as such it is useless. We don't accept it not because we know the prior probability for the alien theory is minuscule; we in fact have no idea what the prior probability is. We dismiss it because even if it were correct, in the absence of knowing anything else about those aliens, the theory is useless.

True, but it wasn't just that comment. It was mainly the two examples that you chose to support your position that made me think you were suffering from some fundamental misunderstanding.

I also think that you are overestimating my ignorance.

Could be. You did get this one right, and it's a biggie:

The real reason why we don't admit the alien theory is because it has no "explainability"; in the sense it's a theory that can explain anything, cannot be used to make predictions, and as such it is useless. We don't accept it not because we know the prior probability for the alien theory is minuscule; we in fact have no idea what the prior probability is. We dismiss it because even if it were correct, in the absence of knowing anything else about those aliens, the theory is useless.